Key will not sync

Hi all, I have a 1997 P38 2.5. I've just put new batteries in one of my keys. It will start the engine with no problems, however it will not unlock the doors remotely. My other key works with no issues. I've tried resyncing it using the hold the lock button down inserting it turning to lock it etc and permutations there of but it still will not lock or open the doors remotely. Any ideas please?

ocm1uk said:

Hi all, I have a 1997 P38 2.5. I've just put new batteries in one of my keys. It will start the engine with no problems, however it will not unlock the doors remotely. My other key works with no issues. I've tried resyncing it using the hold the lock button down inserting it turning to lock it etc and permutations there of but it still will not lock or open the doors remotely. Any ideas please?

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My Thoughts are just check which key it is your using as there is a key No1 and key No 2 if you are using key 2 as the master as often the No1 key gets the buttons worn first and people change what they use as the main key. Try syncing key No1 first and then keyNo2. Worth a try.

Did your fobs work before you changed the batteries?

ocm1uk said:

Hi all, I have a 1997 P38 2.5. I've just put new batteries in one of my keys. It will start the engine with no problems, however it will not unlock the doors remotely. My other key works with no issues. I've tried resyncing it using the hold the lock button down inserting it turning to lock it etc and permutations there of but it still will not lock or open the doors remotely. Any ideas please?

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Insert key. Press unlock button, turn to unlock. Press lock button, turn to lock. Press unlock, turn to unlock. Make sure the RF receiver under the rear parcel shelf is plugged in and operational. Might take a few attempts.

Sorry I've not replied, been away. So I have no idea which is key one or two as there is no stickers on the fobs. The key that doesn't work was in a poor state with flat batteries when I got it, it was sent away for new switches etc and came back with flashing lights. However it would not remotely lock or unlock the car. If I unlocked with the other key the one that wouldn't unlock will start the car. However if I use the blade to unlock the car with the fob that does not unlock remotely it will not start the car. If I use the other key to unlock and start the car then take that out of the ignition and use the one that will not unlock remotely it will start the car. Confused??? Me too.

Another thing I've noticed after sodding about with different procedures, when I put the key in the ignition the red light on the fob flashes. What if anything does that mean?

ocm1uk said:

Sorry I've not replied, been away. So I have no idea which is key one or two as there is no stickers on the fobs. The key that doesn't work was in a poor state with flat batteries when I got it, it was sent away for new switches etc and came back with flashing lights. However it would not remotely lock or unlock the car. If I unlocked with the other key the one that wouldn't unlock will start the car. However if I use the blade to unlock the car with the fob that does not unlock remotely it will not start the car. If I use the other key to unlock and start the car then take that out of the ignition and use the one that will not unlock remotely it will start the car. Confused??? Me too.

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Can only assume that the key that you can start the car with after you unlock with other fob has the correct blade but is not a correct fob. The flashing is caused by the passive coil trying to communicate with the fob. I think you either have a duff fob or the wrong fob fitted with the correct blade. If you have access to a Nanocom, you can read the RF memory, you will possibly find your duff fob is either not sending a signal at all, or the incorrect signal.

Certainly starting to look like that.

Will a Nanocom tell me if I have a 1,2,3 or 4 key. Because if I spen £170 on a number one keyfob I don't want to be still left with one key that works because it's cancelled the other one out.

Valid point.

Do you have memory seats? Do the seat adjust automatically to the key? If so set number 1 memory as far forward as possible and then see which fob does what ... although that requires a working fob!

It also requires the vehicle to be superlocked to make it 'lazy unlock' and move the seats to either memory 1 or 2 if they are fitted.

I have a fob tester that captures the code the key is sending out and from that I can work out what key # it is - but I'm away at the moment, so not home to be able to use it...

The red light on the fob when you put it in the ignition is the passive immobilisation circuit working to get the fob to send the unlock code to the BECM to turn off the immobiliser. The fact that you get this on one fob and then can start the vehicle says to me that the receiver is all working OK - maybe the antenna has been disconnected so the range is reduced though.

My thoughts... maybe the second fob that doesn't flash the red light has a faulty pickup coil, so it's not being triggered by the ignition to send an unlock code. I've heard of a few instances where people have opened up the key fob casings to replace the casing, or repair switches, where they've found the pickup coil component loose/not attached to the PCB. If you don't get the red light flashing when you press either of the buttons, then I'd be checking the battery contacts in the fob and things like that too.

You should be able to sync the keys in the door - yes.. If this isn't happening, then I would first see if the receiver has the antenna connected. There should still be enough range without it connected to get communication, but if there is RF interference around then maybe the signal isn't getting through properly.

If still no joy, then I would also test the microswitches in the drivers door, as these can affect the BECM recognising the key being turned in the door, and if it's not recognising the key being turned, then it might also be messing with the sync procedure. The fact that one of the fobs will sync in the ignition, but not the door, and the other one won't sync at all suggests to me there are more than one problem... one possibly being the door latch if neither will sync in the door, and another problem with the second fob not being triggered by the passive coil around the ignition.

I would be able to be certain without actually seeing the vehicle/hooking it up - but that's my thought process from what I've read

Martyuk, sorry I may have confused the issue a bit. One key fob works perfectly, there is a bit of a loose connection inside which stops the light from flashing now and again but that is not the issue. It just needs a refurb and I can't send it off until I have another key that works.. The issue is the other fob which will not sync with the car. It will start the engine if I open the car with the other fob. Both fobs flash in the ignition the one that works does so for a short amount of time the one that doesn't does it for longer.

By the way the RF antenna is connected. EKA works fine so I'd assume from that that the micro switches are okay. Also it has just come back from being refurbished by a guy recommended on here. He said he had tested it before sending back and said it was transmitting a signal with no problems.

Just carried out the seat test and the Fob that works seams to pair with memory one. Can I assume that the fob that works is in fact key one? The thing that casts doubt in my mind is when you have keys 3 and 4 how does that work with two memory positions?

ocm1uk said:

Will a Nanocom tell me if I have a 1,2,3 or 4 key. Because if I spen £170 on a number one keyfob I don't want to be still left with one key that works because it's cancelled the other one out.

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No.

Just to add only key one is supplied now, had to have new fob couple months ago as both mine gone on the blink, £170 ish.

ocm1uk said:

Just carried out the seat test and the Fob that works seams to pair with memory one. Can I assume that the fob that works is in fact key one? The thing that casts doubt in my mind is when you have keys 3 and 4 how does that work with two memory positions?

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Keys 3 and 4 just lock/unlock the vehicle - they won't lazy unlock and move the seats.
If the second fob has been repaired and doesn't work with the vehicle then there are one or 2 possible scenarios... 1) being that the key is fine and working, but is also a key #1 so it's constantly losing sync when the other key is being put in the ignition, or 2)as mentioned before the other fob is actually from a different vehicle and thus even if it is sending a code, it might be the wrong one for your vehicle.

If I had both fobs then I could read the transmission from both and be able to tell you if they are the same ID being transmitted, or if they are from different vehicles/locksets.

It's late where I am at the moment, so that's about all I can think of after a day at work and a couple of beverages... but when I am home, if you are passing Swindon at all, I'd be more than happy to hook the Nanocom up to the BECM to check the settings against your vehicle (in case it has been replaced some time in the past, and you have one remote fob from the original lockset, and one from the new lockset, but with the correct key blade for the vehicle) and I could also read the key fob transmissions to see if they are from the same lockset too. Without having all the bits in front of me I could only guess as to what's really going on

Thank you all so much for your help. I think, as I only want another key as a spare I'll order a new one, it just means I'll have to resync it when I use it. I'm of the belief that the one that does not work properly has the right blade but is sending the wrong signal. Bit of a bugger really but it seems this vehicle has more surprises than the guy who sold it time was prepared to admit. I really want to keep it but it really depends on how much money I need to spend on it. Thanks all again.

Key 4 probably a safe bet. Or wait and see Marty in the New Year.

Just seen you're in East Sussex. If you can pop along to the Brighton area and see Rick-the-pick then he can probably sort something.